Active members: They regularly attend the weekly sessions of their praesidium and pray daily the prayer of the Legion, the Catena Legionis, which consists essentially of the Magnificat and some shorter prayers. Their main role lies in active apostolate for the Legion and the Church. Active members under the age of 18 are not allowed to give the "Legion promise" until they turn 18. Members 18 and under are considered Juniors, and are able to hold any office except President in their praesidium.
Auxiliary members: They support the Legion through their prayer. They pray the whole booklet of Legion prayers, the Tessera, every day. The Tessera consists of the Invocation, prayers to the Holy Spirit, the Rosary, the Catena, and the concluding prayers of the Tessera.
The St. Pius X praesidia of the Legion meets weekly, on Tuesdays at 7:00PM in the New Library.
For all sessions, the Altar of the Legion is set up. This consists of a statue of the Virgin Mary that is placed on a white tablecloth that has "Legio Mariae" written on it. On the two sides of the statue are placed two vases with flowers, often roses (the flower connected with Mary). On the front ends of the cloth stand two candlesticks with burning candles. On the right side of Mary, the vexillium Legionis (standard of the Legion) is placed. It is made out of metal and onyx and shows the Holy Spirit in the form of a dove, as well as the Miraculous Medal.
During the meetings, all prayers of the Tessera are said. The sessions start out with the introductory prayers to the Holy Spirit and Mary. These include five decades of the Rosary. The following part of the session includes a spiritual reading and administrative matters. Each member tells in short words how he or she has fulfilled their tasks assigned to them at the previous session. They also discuss and/or read a chapter from the Handbook of the Legion. Then the Catena Legionis is prayed, afterwards the Spiritual director or (if he is absent) the President holds a short sermon about spiritual matters (allocutio). Finally, the new tasks for the legionaries are distributed. Each meeting ends with the concluding prayers of the Tessera and a prayer for Frank Duff's beatification.